Caster system used with wooden or plastic legs for furniture

ABSTRACT

A caster and leg assembly for supporting a piece of furniture on a floor. The assembly includes a caster affixed within a recessed area formed in the bottom of a wooden or plastic furniture leg to create a strong support for the furniture as well as create a good appearance. The caster has at least one spherical roller supported within the housing to allow the furniture to be readily movable omnidirectionally. With one spherical roller, the weight of the furniture acts at the center of the spherical roller. In one embodiment, there are three spherical rollers located equidistant from the vertical center line of the assembly to support the furniture weight equally by the spherical rollers. A glide can be readily attached and detached from the bottom of the caster and, when attached, the glide cup covers the spherical rollers and presents a flat, planar bottom surface.

REFERENCE TO RELATED CASES

This patent application is a continuation-in-part application based upon and claiming priority of U.S. patent application Ser. No. 10/295,666, filed Nov. 15, 2002 and entitled CASTER ASSEMBLY FOR A BED FRAME MEMBER OR FURNITURE and which is, in turn, a continuation of U.S. patent application Ser. No. 09/519,725 filed Mar. 3, 2000, now U.S. Pat. No. 6,568,031, issued May 27, 2003.

BACKGROUND OF THE INVENTION

The present invention relates to a caster assembly for a use with furniture, and, more particularly, to a caster assembly adapted for use with a wooden or plastic leg of a piece of furniture.

In general, there are many types of furniture casters that are available and which are affixed or incorporated into the legs of such furniture to enable that particular piece of furniture to be readily rolled from one location to another.

Accordingly, the caster assemblies for furniture normally have rotatable rollers to facilitate the movement of the furniture. Such caster assemblies also generally have an elongated stem that interfits into the furniture. That stem has a central longitudinal axis along which is directed the weight of the furniture The roller itself is mounted to the assembly within a housing and the roller is rotatably mounted to that housing to roll about a central axis that is parallel to the plane of the floor. The housing is also pivotally mounted to the furniture leg so that the roller itself can not only rotate about its axis, but the housing, including the roller itself, can also pivot 360 degrees about the main longitudinal axis of the stem.

The swiveling action or movement is necessary to correctly align the roller for movement in the proper direction, however, such swiveling movement can be generally difficult to accomplish. For one reason it is apparent that all of the rollers supporting the furniture must be correctly aligned in order to easily move the furniture. In most instances, the rollers are positioned in various directions and it is therefore necessary to align all of the rollers at the initial movement of the furniture. With the weight of many pieces of furniture, there is considerable friction acting against the swiveling action of the caster assembly and the problem is aggravated by the need to align some 4-5 rollers in order to roll the furniture. Additionally, the roller is often embedded into an indentation in the carpet that lies along the surface of the roller and the roller must be moved out of the indentation to swivel. As such, therefore, while the swivel action is necessary to properly move the furniture, it can be somewhat difficult to get the swivel action to operate easily and thus the initial movement of the furniture is not easy to accomplish, particularly when the piece of furniture is on carpeting with padding.

The typical conventional caster for use with carpet is a cylindrical member that contacts the floor at a certain finite distance away from the longitudinal, vertical axis of the stem so that the roller can pivot to a position determined by the direction the furniture is being moved and then the roller rotates to make that movement easy to accomplish. A typical roller caster assembly used on a bed frame is shown and described in U.S. Pat. No. 4,007,502 of Mis. As can be seen in the Mis patent, the roller is offset with respect to the downward force that acts through a stem and, as will become clear, this typical caster of Mis suffers from certain inherent weaknesses.

Thus, since the contact point between the roller and the floor is located at an offset dimension from the longitudinal, vertical axis of the stem along which the weight of the furniture is directed, a bending moment is created based on the weight of the furniture acting downwardly on the stem and the distance between the location of that force along the longitudinal axis of the stem and the point where the roller contacts the floor to support the frame.

One of the difficulties with such casters, therefore, is that the bending moment created by that offset creates stress on the caster assembly and can cause a premature failure of the caster assembly or the furniture itself, thereby disabling the entire unit. The problem is aggravated, of course, with legs having increased degrees of weakness, and in particular, with the use of plastic legs as shown and described in U.S. Pat. No. 3,828,376 of Miller. Accordingly, it would be advantageous to have a caster assembly that has rollers that provide better support for the furniture and which do away with the offset that causes the bending moment and the premature fracture of essential components such as the leg of the furniture, thus avoid damaging the furniture. There are rollers that have ball bearings that may aid in the swiveling of the roller or aid in the rolling motion of the roller itself but most require the offset and the consequent swiveling action to operate in moving the furniture.

Other prior art furniture support assemblies have, in fact, utilized a plurality of elements that contact the floor and examples are illustrated in U.S. Pat. No. 1,060,076 of Glowacki and U.S. Pat. No. 1,282,396 of Friend. In the aforementioned patents, however, while a plurality of members contact the floor and thus allow the weight to be borne by a plurality of elements, there is a further problem with respect to the ease of moving such casters as the spherical members are clamped into the housing supporting the particular piece of furniture and the spherical contact members do not thus freely rotate to allow the ready movement of the furniture. Accordingly, in Glowacki, the balls that actually contact the floor are clamped tightly into a circular dome and thus are not movable with respect to the dome as the furniture is moved. Therefore, while the prior art did consider the support of the weight of a piece of furniture on a plurality of contact members, the moving of the furniture was not enhanced and only the idea of a strong support was considered and appreciated.

In addition to caster assemblies, there are also glide assemblies that are mounted to the various pieces of furniture and have a generally flat, planar bottom contacting the floor. The glide assemblies are preferably used where the furniture is located on a hard or slippery surface such as a wood or tile floor and thus the flat bottom does not easily slip or cause damage to the floor itself. With such flooring surfaces, the user of a caster having a roller causes unnecessary sliding or rolling as contrasted to the intended use of a rug roller or caster on a carpeted surface where the friction with the carpet reduces the mobility of the roller or caster.

Glide assemblies are inherently stronger than caster assemblies since the weight of the bed frame using a glide acts along the longitudinal axis of the glide directly to the point of contact with the floor, and thus, there is no offset from that axis to the point of contact and, hence, no bending moment. In addition, of course, the glide planar surface allows more surface contact with the floor and thus carries the weight of the furniture over a wider area so as to provide a better distribution of that weight. As such, the glide assembly has enhanced strength and stability over the caster assembly.

A further alternative is with the use of a caster cup that is generally cup shaped that is slid underneath a roller of a caster assemble to aid in slowing the mobility of the caster and to stabilize the piece of furniture, particularly when used on a slippery flooring surface. The caster cups, however, are easily displaced from under the roller since they are not firmly locked to or attached to the caster assemblies and are thus difficult to maintain in place when the furniture is moved during the normal use of the furniture. Thus, over time, the caster cups become displaced with respect to the roller and no longer serve their intended purpose.

As a further problem with many of the aforedescribed caster assemblies, since the caster roller needs to pivot 360 degrees about its vertical axis, it is very difficult to build the caster assembly into a wooden or plastic leg of the furniture and, therefore, the caster for a wooden or plastic leg is simply screwed into the bottom of a leg by means of a threaded stem and, accordingly, creates a weak point as well as a less than pleasing appearance of the caster affixed to the bottom of a leg.

Accordingly, it would be advantageous to have a caster assembly that can be used with a wooden or plastic furniture leg that can be recessed into the leg so that the overall appearance is pleasing and the caster fits in with the exterior contour of the leg. It would also be advantageous to have a caster assembly for a wooden or plastic furniture leg wherein the caster assembly has a strong connection to the furniture leg and where there is no upstanding stem or other member that can introduce a weak point into the leg/caster combination. It would be still further advantageous to have a caster assembly for a wooden or plastic furniture leg where there is a glide that can be removably affixed to the bottom of the caster so that the user can readily convert the caster to a glide and vice versa.

SUMMARY OF THE INVENTION

Now, in accordance with the present invention, an improved caster and leg assembly is shown that overcomes the difficulties heretofore explained. In the present invention, the caster assembly is adapted for use with furniture having a wooden or plastic leg. The structure of the caster assembly comprises a housing that is attachable to the wooden or plastic leg of a piece of furniture by interfitting into a recessed area provided in the lower end of the furniture leg. By the interfitting of the caster into the bottom of a wooden or plastic leg, the combined caster and leg assembly can present an overall smooth, streamlined exterior surface as well as maintain the strength of the support for the furniture. As a further advantage, the present caster can be added or retrofitted to an existing furniture leg by an owner of the furniture or can be installed by the original manufacturer of the furniture.

The assembly has a generally vertical elongated axis or centerline such that the weight of the bed is transmitted to the housing of the caster and leg assembly generally along the centerline that is centrally located with respect to the housing. At the bottom of the caster there is at least one, and preferably three, spherical rollers that contact the floor and allow the piece of furniture roll with respect to the floor for the convenience of moving the furniture from one location to another location. The spherical rollers are mounted to a housing having a cavity and a plurality of small spherical balls are freely located between the housing and the spherical rollers such that each spherical roller or rollers freely rotate omni-directionally, that is, the roller or rollers are free to rotate about center points and thus can rotate in any direction. As such, therefore, the spherical roller(s) can rotate in any direction that the user pushes the piece of furniture in relocating that piece of furniture and no additional force is needed to commence the initial movement of the furniture.

In the preferred embodiment, there are at least three spherical rollers, more preferably three spherical rollers, so that the weight of the furniture and its supported components and weights are distributed at three contact points with the floor to better distribute the weight and prevent severe indentations in the floor. In addition, the location of the rollers is such that they are equidistant from the elongated, vertical central axis or centerline through which the weight of the furniture acts on the caster and leg assembly and thus, the single bending moment is eliminated and the structure has enhanced strength and stability. As stated, with the three rollers, each is still mounted to a housing such that the rollers move freely in any direction and do not need to be aligned to the direction of movement of the furniture by pivoting about a central axis or centerline. In effect, the need for a swiveling function is completely eliminated.

Accordingly, the caster assembly of the present invention has the strength of the prior art glide assemblies since the single offset has been eliminated and, of course, the assembly therefore does not need to swivel in order to allow the furniture or bed to be moved in any direction. With the offset and the need to swivel eliminated, the aforedescribed problems associated with those features are also eliminated.

As a further feature of the present caster assembly, a glide is readily attachable and detachable to convert the caster assembly from a roller caster to a glide function and vice versa. When attached, the glide alters the function of the caster assembly from a roller caster where the rollers are in contact with the floor to a glide function where the caster assembly is transformed into a glide. Accordingly, the bottom surface of the glide is a planar surface as in the case of most glides and the glide is attached and detached without the need for special tools or equipment. It should be noted, that the bottom surface of the glide is referred to as planar, however, typically it is an effective planar surface as there is normally a central portion of the bottom surface that is displaced upwardly and only a peripheral planar area is actually in contact with the floor. The attachment and detachment can be readily accomplished in the home by an installer that can determine at the time of installation whether or not the glide or roller function is applicable.

The resulting caster assembly therefore combines the strength of the glide assemblies with the mobility of a roller caster assembly and provides the user with the option of using the spherical rollers to contact the floor or easily transform the caster assembly to add a glide so that the assembly can be used on slippery surfaced floors.

In such situation, instead of changing the caster itself, the user only needs to attach the glide to the bottom of the caster housing whereupon the rollers are hidden and the lower surface of the caster assembly is a flat surface and therefore suitable for a hard wood or other slippery surface floors. The glide is locked on to the caster housing and does not become detached during the use or movement of the furniture.

In one embodiment the attaching and detaching of the glide is accomplished by an interfitting of the glide to a lower shroud that is positioned at the lower portion of the caster assemble. That lower shroud itself has a plurality of elongated openings generally formed as arcs of a circle with a larger opening portion and a smaller opening portion. The glide has a similar number of upwardly directed tabs that are adapted to fit into the larger post of the openings in the lower shroud. Each of the tabs has an upper lip that is dimensioned to fit through the larger opening portion of the elongated openings but which cannot fit through the smaller opening portions. A locking projection is formed on each of the elongated openings to securely lock the upwardly directed tabs to the lower shroud.

By simply rotating the glide, the tabs are rotated to a position where the tabs are moved into the smaller opening portions where the lips are captured by the lower shroud since the lips cannot pass through the smaller portion openings and the glide is securely retained in position affixed to the lower shroud. By such means, the glide is locked into position onto the lower shroud of the caster assembly and will not come apart while the furniture or bed is being used or even during movement thereof. Once affixed to the lower shroud, the glide thus converts the caster assembly to a glide function, however, even then, the weight is still distributed through the three spherical rollers that bear against the glide and carry the weight of the furniture.

Other features of the caster assembly will become more apparent in light of the following detailed description of a preferred embodiment thereof and as illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a conventional bed frame with which the present invention can be employed;

FIG. 2 is a side plan view of a typical prior art caster assembly used in current bed frames;

FIG. 3 is a perspective view of a glide that is also currently used in present bed frames;

FIG. 4 is an exploded perspective view of a caster assembly constructed in accordance with the present invention;

FIG. 5 is a bottom plan view of the caster assembly of FIG. 4;

FIG. 6 is a side cross-sectional view of the caster assembly constructed in accordance with the present invention;

FIG. 7 is a side cross sectional view of the caster assembly having the glide component attached thereto;

FIG. 8 is a perspective exploded view of the preferred embodiment of the caster assembly of the present invention;

FIG. 9 is a bottom perspective view of an upper shroud component of the preferred embodiment of the present invention;

FIG. 10 is a side cross sectional view of a stem housing component of the preferred embodiment;

FIG. 11 is a top perspective view of the component of FIG. 10;

FIG. 12 is a bottom perspective view of the component of FIG. 10;

FIG. 12A is a bottom plan view of the component of FIG. 10;

FIG. 13 is a top perspective view of the ball cup component of the preferred embodiment;

FIG. 14 is a bottom perspective view of the ball cup component of FIG. 13;

FIG. 15 is a side cross sectional view of the component of FIG. 13;

FIG. 16 is a top perspective view of the lower shroud component of the preferred embodiment;

FIG. 17 is a top perspective view of a glide cup component of the preferred embodiment;

FIG. 18 is a side view of the component of FIG. 17;

FIG. 19 is a side cross sectional view of the preferred embodiment of the caster assembly of the present invention;

FIG. 20 is a perspective view of bed rails connecting between a headboard and a footboard including a cross member;

FIG. 21 is a perspective view of a caster assembly of the present invention adapted to be used with the side rail construction of FIG. 20

FIG. 22 is a perspective view of a couch utilizing the caster assemblies of the present invention;

FIG. 23 is a cross sectional view of a caster assembly of the present invention fitted into a wooden of plastic leg for use with furniture;

FIG. 24 is a cross sectional view of a still further embodiment of the caster assembly of the present invention;

FIG. 25 is a cross sectional view of a further embodiment where only one spherical roller is used;

FIG. 26 is a perspective, cutaway view of a box spring showing the affixation of a caster thereto;

FIG. 27 is a side view of a caster affixed in the manner illustrated in FIG. 26;

FIG. 28 is a perspective view of a box spring illustrating a further means of affixing a caster to a box spring; and

FIG. 29 is a perspective view of a caster that is used in the affixation means illustrated in FIG. 28.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIG. 1, there is shown a perspective view of a conventional bed frame with which the present invention can be applied. It should be noted, however, that while the FIG. 1 embodiment of the present invention is initially shown and described specifically for use with a bed frame, the broader aspects of the invention make it applicable to any item of furniture with the same advantages and improvements.

Thus, in FIG. 1, the conventional bed frame is comprised of a pair of side rails 10 and cross members 12. The number of cross members may vary depending upon the particular bed, and its size, that is, there may be one or more intermediate cross members that provide additional support to the box spring and mattress when assembled. The side rails 10 and cross members 12 are normally constructed of L-shaped angle iron. As shown, there are legs 13 that are normally located on the cross members 12 or the side rails 10 depending on the particular construction and, if any further cross members are used in the bed frame, there may also be one of more additional legs extending downward from those cross members. At the bottom of the legs 13, there are affixed thereto casters 14 that are in contact with the floor.

Taking now FIGS. 2 and 3, there is shown, respectively a side view of a typical caster 14 and a perspective view of a typical glide 16. Either the caster 14 or the glide 16 can be used as a support for a bed frame and each is preferably used in differing circumstances. Taking first the caster 14, as can be seen, the conventional caster comprises a roller 18 that is normally cylindrical and which rotates about an axis, indicated by the letter A, that is positioned parallel to the floor. The caster 14 includes a metal housing 20 having an upstanding stem 22 that extends upwardly and which is inserted into the leg or other support point on the piece of furniture.

The roller 18 thus rolls freely about its axis A in the direction at a right angle to that axis, however, the roller 18 obviously does not freely rotate to move the piece of furniture or bed frame if the user attempts to move that furniture in the direction along the axis of rotation of roller 18. To accomplish moving the furniture in such direction, therefore, it is necessary for the housing 20 to swivel about the axis B of the upstanding stem so that the roller 18 becomes aligned with the proper path of travel. As will be later explained, in order for the housing 20 to swivel there is a necessary offset between the axis B and the point of contact of the roller 18 with the floor.

In the normal movement of the caster 14, the swiveling movement takes place quite automatically as the furniture, such as a bed, is moved in the desired direction since the swivel effect takes place as the initial movement occurs and the roller 18 becomes aligned properly for that direction of movement. As explained, however, the swiveling action can be difficult to accomplish and the initial movement of the furniture therefore is not easily facilitated.

In addition to the swiveling problem, the normal caster, as shown in FIG. 2 also suffers from an inherent weakness in that the weight of the furniture is directed downwardly along the axis B of the upstanding stem 22 whereas the contact with the floor and the support point for the furniture occurs at the point 24 at the bottom of the roller 18. As can be seen, there is an offset or finite distance between the direction of the load imposed by the furniture along the axis B and the point at which that load is supported by the floor. That offset is necessary to accomplish the swiveling action, however, it also sets up a stress in the caster by creating a bending moment in the caster 14 that is always present and can lead to premature failure of the caster 14 and/or the connecting leg.

Accordingly, while the caster 14 is certainly helpful in providing mobility to the piece of furniture, there are inherent weaknesses that can lead to a failure of the caster or the leg of the bed frame itself that are always present due to the basic design of the caster and can lead to the possibility of damage to the caster or other structural components of the bed frame.

Turning to FIG. 3, a glide 16 is shown and which is also used with furniture as a support, particularly where the piece of furniture is located on a hardwood or tile floor. Again, the glide 16 includes an upstanding stem 26 that is adapted to be inserted into the leg or other support point of the furniture. The glide 16 has a flat bottom surface 28 and is thus preferred on the aforementioned floors and, unlike the caster 14, is exceptionally strong since the weight of the furniture acting downwardly along the main axis of the upstanding stem 26 is directly supported by the contact with the floor and there is therefore no offset to that force that can cause stress. The glide is typically used on a bed rail assembly and can be used on carpeted floor for strength, however the added friction between the bottom of the glide and the carpeted floor make the potential of damage to the bed structure more likely.

On the other hand, of course, with the use of glide 16, the mobility of the furniture is sacrificed. Not only is the mobility of the furniture sacrificed, but there is an additional weakness in the glide 16 if the furniture is attempted to be moved since the glide 16 does not move readily along a carpet, for example, and any attempt to slide the furniture along that type of flooring can cause the glide to get caught on the material and cause the glide to snap off from the upstanding stem 26 or worse, to break off a leg or other part of the furniture. This is particular true where the glide is positioned at the center of a bed frame affixed to a cross member since that location is already a relatively weak structure and is subject to bending and breaking.

Therefore, since the present caster assembly 30 does not need to swivel in order to allow the piece of furniture to be moved, as was the case with the prior art rollers, the present caster assembly 30 can be affixed to the piece of furniture in a wider variety of ways, such as being attached offset to the side of the furniture as the center of the caster assembly 30 need not be the particular point of the caster assembly that is actually affixed to the furniture. With the prior art swivel casters, particularly those screwed into the furniture, such versatility was not present and the means and location of attachment to the furniture was limited.

Turning now to FIG. 4, there is shown an exploded view of a caster assembly 30 constructed in accordance with the present invention. In the Figure, the caster assembly 30 includes an upstanding stem 32 that again, is adapted to enter and be secured to the particular piece of furniture to which the caster assembly 30 is attached. As noted, the stem 32 will be described that interfits with a leg of a bed frame assembly, however, the stem 32 may have a flat flange at its upper point with suitable holes so that the caster assembly can be secured to a piece of furniture by means of wood screws or other securing means. A housing 34 is provided and from which the upstanding stem 32 extends and within which is positioned a plurality of spherical rollers 36. In the preferred embodiment, and as is shown in FIG. 4, three spherical rollers are utilized. Each of the spherical rollers 36 extend downwardly external of the housing 34 and, as such, contact the floor when in position supporting a piece of furniture.

In this embodiment, the spherical rollers 36 can be formed of plastic material, particularly a plastic having good lubricity and a good memory, one example of which is available commercially from the DuPont Company under the trademark DELRIN. That same material can be used for other components of the caster assembly 30 such as the housing 34. A glide cup 38 is also provided that is readily attached and detached from the housing 34 so that the contact with the floor can be by means of the spherical rollers 36 or, at the option of the user, by contact with the flat, planar bottom 40 of the glide cup 38. The glide cup 38 can also be made of the same plastic material as previously described.

In order to allow the glide cup 38 to be readily attached and detached to the housing 34, there is provided at the lower perimeter of the housing 34, at least one projection 42 that extends outwardly from the lower perimeter. Again, in this embodiment, there are a plurality of such projections 42 extending from the housing 34. Glide cup 38 has an upstanding flange 44 having formed therein, an internally facing ridge 46 with a plurality of recesses 48 that dimensionally coincide with the projections 42 on the housing 34. Thus when the glide cup 38 is to be attached to the housing 34, the glide cup 38 is positioned over the lower periphery of the housing 34 and the projections 42 fit through the recesses 48 so that the glide cup 38 can be fully moved over the lower periphery of the housing 34.

The projections 42 thus pass through and clear the internally facing ridge 46 after passing through the recesses 48 such that the glide cup 38 can be simply rotated a predetermined amount and lock the projections 42 behind the internally facing ridge 46 so that the glide cup 38 is securely attached to the housing. In the position with the glide cup 38 attached to the housing, the caster assembly 30 acts as a glide and the spherical rollers 36 are contained within the glide cup 38. As is obvious, therefore, the glide cup 38 can, by another predetermined rotation, be just as easily detached from the housing 34 so that the spherical rollers 36 can contact the floor.

When the glide cup 38 is installed, the spherical rollers 36 touch and actual bear on the upper surface of the glide so that, in use, the weight of the. bed or other furniture is distributed through the spherical rollers 36 to the glide cup 38 such that the weight of the furniture is well distributed to the glide cup 38 and there is no weight acting on any of the projections 42 or other likely breakable components.

The spherical rollers 36, as can be seen, preferably have centers of rotation and thus are free to rotate omni-directionally, that is, in any direction about their center point of the spherical shape. In addition, in the preferred embodiment, the centers of the spherical rollers 36 are positioned equidistant from the main axis of the upstanding stem 32 so that the weight of the furniture that acts along the main axis of the upstanding stem 32 is equally distributed among the spherical rollers 36 in their contact with the floor. With the weight distribution equally divided, the overall weight is borne by the main axis of the caster assembly 30 and thus through the strength of the assembly. Accordingly, the present caster assembly 30 provides the mobility of the prior art casters while having the strength and structural integrity of the prior art glides. In addition, with the addition of the glide cup 38 the caster assembly 30 can also have the non-marring flat planar surface to contact the floor whenever desired and without difficulty.

Turning now to FIG. 5, there is shown a bottom plan view of the caster assembly 30 constructed in accordance with the present invention and with the glide cup 38 not attached thereto. In this Figure, the physical layout of the spherical rollers 36 can be further explained. In particular, the main, longitudinal axis of the upstanding stem (not shown in FIG. 5) is at the center point 50 of the caster assembly 30 and the weight of the furniture is therefore concentrated along that axis and therefore acting downwardly at about the center point 50. Also shown are the center points 52 of the spherical rollers 36. Thus, it can be seen that the center points 52 of the spherical rollers 36, in the preferred embodiment, are all equidistant from the main longitudinal axis of the upstanding stem so that the weight of the furniture is equally distributed among the three spherical rollers 36 and along the center and the structural strength of the caster assembly 30.

Turning next to FIGS. 6 and 7, there is shown, respectively, a side cross sectional view of the caster assembly 30 without the glide cup 38 attached and a side cross sectional view with the glide cup 38 attached. The spherical rollers 36 may be provided in commercially available self-contained cartridges 54 that can be inserted into suitably shaped holes 56 formed in housing 34. In order to allow the spherical rollers 36 to freely rotate about their center points 52, a plurality of small spherical balls 58 are freely position within the cartridges 54 and freely movable within an annular recess 59 and which allow the spherical rollers 36 to be able to rotate in any direction readily and with a minimum of friction. While a annular recess 59 is shown, the same omni-rotation of the spherical rollers 36 can be accomplished, albeit less efficiently, without the use of the annular recess 59 such that the small spherical balls 58 are simply located at the upper surface of the spherical rollers 36. In a still further less efficient construction, the small spherical balls 58 can be eliminated altogether. Such mechanisms are readily available commercially including the spherical rollers contained within a housing with small spherical balls freely floating intermediate the housing and the spherical rollers 36 to allow the spherical rollers 36 to freely rotate about their center points in any direction, that is, omni-directionally.

In FIG. 7, the addition of the glide cup 38 can be seen with the internally facing ridge 46 locked in position behind the projections 42 so that the glide cup 38 is securely affixed to the housing 34 and the spherical rollers 36 are covered by the glide cup 38 and out of operational use.

Turning now to FIG. 8, there is shown a perspective, exploded view of the preferred embodiment of the caster assembly 70 of the present invention and in view of a later more detailed description of the individual components, a brief description of those components will be initially discussed and new designation numbers assigned even though many components are the same as or similar to the components used in the prior embodiments.

Accordingly, as shown in FIG. 8, there is a spindle 72 that, as explained, is used to affix the caster assembly 70 to the particular piece of furniture. Atop of the spindle 72 is positioned a bushing 74 that is preferably of a plastic material such as polypropylene. The bushing 74 enables the caster assembly 70 to be inserted into the female opening normally provided in furniture, including bed frames and the structural members that make up beds in general. The bushing 74 is pressed onto the spindle 72 and is thus held thereto by an interference fit. By convention, the components will also be referred to as upper and lower throughout and such reference shall be intended to denote the upper direction as toward the piece of furniture and the lower direction to be towards the floor on which the furniture is supported. By that convention, therefore, the bushing 74 is positioned on the upper portion of the spindle 72 and the lower portion of the spindle 72 extends through an upper shroud 76 through an opening 78.

The lower portion of the spindle 72, when assembled, further passes through a central bore 80 formed in a stem housing 82. As will be seen, the spindle 72 is in an interference fit in the central bore 80 such that the stem housing 82 is pressed on to the spindle 72 to affix the spindle 72 firmly to the stem housing 82. The spindle 72 continues with its lower end fitted, again, in an interference fit, into the bore 84 of a ball cup 86. A plurality of spherical rollers 88 are fitted within the ball cup 86 by a snap fit as will be explained and a plurality of smaller balls 90 are located atop of the spherical rollers 88 to aid in the omni-directional rotation of those spherical rollers 88.

Beneath the spherical rollers 88, there is positioned a lower shroud 92 and which is affixed to the upper shroud 76 by means such as drive screws 94. Finally, as shown in the FIG., there is a glide cap 96 that is removably affixed to the lower shroud 92 so as to be easily attached and detached from the lower shroud 92.

Turning now to FIG. 9, taken along with FIG. 8, there is shown a bottom perspective view of the upper shroud 76 and which has in its interior a plurality of locating ribs 98 and bosses 100 that extend downwardly to receive the drive screws 94 when the lower shroud 92 is affixed to the upper shroud 76. In addition, as can be seen, there is an annular flange 102 that extends downwardly into the interior of the upper shroud 76 and which has a plurality of slots 104 formed therein. In the preferred embodiment, the upper shroud 76 is formed of a molded plastic material such as polypropylene.

With reference to FIG. 10, taken along with FIG. 8, there is shown a side cross sectional view of the stem housing 82. In that FIG. the central bore 80 can be seen through which the lower portion of the spindle 72 passes in an interference fit in affixing the spindle 72 to the stem housing 82. As also can be seen, the is a spherical indentation 106 formed in the lower surface of the stem housing 82 having a predetermined radius and center point and an annular recess 108 extending upwardly from the lower surface of the stem housing 82 and surrounding the spherical indentation 106. As shown, of course, there are preferably three spherical indentations 106 that conform to the preferred number of spherical rollers 88 employed in the preferred embodiment. In addition, there is formed in the stem housing 82, a plurality of upwardly directed bosses 110, having internal bores 112, the purpose of which will be later explained.

Turning now to FIGS. 11, 12 and 12A, taken along with FIG. 8, there is shown, respectively, a top perspective view, a bottom perspective view and a bottom plan view of the stem housing 82. In FIG. 11, there can be seen, a plurality of ribs 114 extending outwardly from the central bore 80 and which preferably comprise three ribs 114 wherein the upper edges 116 of such ribs 114 fit into the slots 104 (FIG. 9) of the upper shroud 76 when the overall caster assembly 70 is assembled into a completed unit. As further shown in FIG. 11, the upwardly directed bosses 110 comprise three bosses 110 and the internal bores 112 of those bosses 110 are dimensioned so as to receive the bosses 100 of the upper shroud 76 (FIG. 8), again, when the overall caster assembly 70 is assembled. Further enlarged bores 118 are formed in the stem housing 82 along the internal bores 112 in the lower surface of the stem housing 82 (FIGS. 10 and 12) and are also utilized to allow the overall caster assembly 70 to be compactly and sturdily assembled together into the completed unit. In FIG. 12A, there can be seen the lower portion of the annular recess 108 and illustrating that the annular recesses 108 are annular and fully circular in form and are located between the outer edges 105 of the spherical indentations 106 and the inner diameter 107 within the inner housing 82.

Turning now to FIGS. 13 and 14, taken along with FIG. 8, there is shown, a top perspective view and a bottom perspective view, respectively, of the ball cup 86 of the present invention. There is thus shown, the bore 84 within which the lower end of the spindle 72 terminates in an interference fit upon assembly. Surrounding the bore 84 are openings 120 that, as will be seen, contribute to the overall compactness of the completed assembly. Three circular flanges 122 extend downwardly from the ball cup 86 and contain the spherical rollers 88. The internal cavity 124 of those circular flanges 122 is formed in a generally spherical configuration and includes a circular ridge 126 that is used to contain those spherical rollers 88 in a snap fit. As seen, with reference to FIG. 13, the upper peripheral surface 128 surrounding each of the internal cavities 124 is slightly chamfered inwardly in a gently sloping surface leading into the internal cavities 124. Slightly raised flanges 130 partially surround the upper periphery of the internal cavities 124.

Turning to FIG. 15, there is shown a side cross sectional view of the ball cup 86 such that one of the internal cavities 124 can be seen with the internal spherical configurations. As will be seen, the configuration and the dimensions of the spherical internal cavity 124 as such that the spherical rollers 88 can simply be snapped into those internal cavities 124 and retained in that position where the spherical rollers 88 are contained but can freely rotate in any direction, that is, omni-directionally. In the preferred embodiment, the spherical rollers 88 are comprised of an acetal plastic material.

Next, in FIG. 16, taken with FIG. 8, there is shown a top perspective view of the lower shroud 92 and which has its external peripheral surface mate with the external peripheral surface of the upper shroud 76 to contain the components of the completed caster assembly 70. In this FIG., the lower shroud 92 includes three bosses 132 that extend upwardly and, when the caster assembly 70 is assembled, the bosses 132 extend through the openings 130 of the ball cup 86 (FIGS. 13 and 14) to contact and fit into the enlarged bores 118 of the stem housing 82 (FIGS. 11 and 12). The lower shroud 92 also includes a plurality, (preferably three) of openings 134 having circular flanges 136 that extend upwardly and through which the circular flanges 122 of the ball cup 86 pass (FIG. 14) in the assembly of the overall caster assembly 70.

In the lower surface 138 of the lower shroud 92, there is formed a series (three) of elongated slots 140 having a longitudinal axis forming a circular arc. As can be seen, the elongated slots 140 comprise a larger width portion 142 and a smaller width portion 144 about that arced configuration. In addition, there are small projections 145 formed at the entrance to the smaller width portions 144 that extend slightly into the elongated slots. The purpose for the elongated slots 140 will become apparent from a discussion of the next Figures.

Thus, turning to FIGS. 17 and 18, taken along with FIG. 8, there is shown a top perspective view and a side view of the glide cap 96 that is used with the present invention. As explained, the glide cap 96 is designed to be easily affixed to and removed from the overall caster assembly 70 to convert the caster assembly 70 between its different functions of action as a roller assembly and a glide assembly. Thus, in FIGS. 17 and 18, there is a lower surface 146 that is generally planar and is adapted to contact the floor when the glide cap 96 is installed with the caster assembly 70. A plurality of tabs 148 are molded into the glide cap 96 and which, itself is preferably a plastic molded polypropylene material. Again, the preferred number of tabs 148, as shown, is three. At the upper end of the tabs 148, three are formed lips 150 that are directed outwardly with respect to the center of the glide cap 96.

Thus, returning to FIG. 16, taken along with FIGS. 17 and 18, the interaction of the tabs 148 and the elongated slots 140 can be explained. In affixing the glide cup 96 to the lower shroud 92, the tabs 148 align with the larger width portions 142 of the elongated slots 140 in the lower surface 138 of the lower shroud 92 such that the glide cup 96 can be positioned to insert those tabs 148 through the larger width portions 142. Thereafter, by merely rotating the glide cup 96, the tabs 148 can enter the smaller width portion 144 where the lips 150 are captured by the lower surface 138 of the lower shroud 92. The smaller width portions 144 prevent the passage of the lips 150 therethrough and thus the glide cup 96 is readily and easily retained to the lower shroud 92 so that the caster assembly 70 acts as a glide. As the tabs 148 pass by the small projections 145, the tabs 148 are effective locked into position and do not readily become detached by normal use of the bed or movement thereof. Obviously, the removal of the glide cup 96 is just as easily accomplished by a reversal of the process, that is, the glide cup 96 is rotated to the position where the tabs 148 are in alignment with the larger width portions 142 so that the lips 150 can pass through the elongated slots 140 and the glide cup 96 removed.

Taking FIG. 19, there is shown a side cross sectional a view of the completed and assembled caster assembly 70. In the FIG., therefore, it can be seen that the spherical rollers 88 are fitted into the ball cup 86 and are freely rotatable therein omni-directionally and the plurality of smaller balls 90 freely move within the annular recess 108 to allow the movement of the spherical rollers 88. Those smaller balls 90 move over the upper surface of the spherical rollers and are contained within the area between the spherical rollers 88 and the spherical indentations 106 in the stem housing 82. In the assembled form, as shown in this FIG., therefore the drive screws 94 affix the lower shroud 92 to the upper shroud 76 to encase all of the components in the overall caster assembly 70 in accordance with the present invention. Alternatively, of course, in the place of drive screws 94, other means could be used, such as self tapping, thread cutting screws.

Turning now to FIG. 20, there is shown a perspective view of bed rails 60 connecting between a headboard 62 and a footboard 64 and showing a cross member 66. As can be seen, with the use of bed rails 60, the vertical height of the bed rails 60 above the floor is not a standard dimension and depends on the height of the legs of the headboard 62 and the footboard 64. Accordingly the cross member 66 must have a support that is adjustable as to height. In such case, a caster assembly 30 is provided that supports the center of the cross member 66 and is adjustable in height but still has the advantages as previously explained with respect to mobility and strength of the caster assembly 30. The cross member 66 may also be of the type that is universally adapted for use with bed rails and is further disclosed in a U.S. Patent application filed on the same day as the present application and entitled UNIVERSAL TENSION SPRING SUPPORT MEMBER FOR BED RAILS OR BED FRAME, and the disclosure of that application is incorporated herein by reference.

Thus, turning to FIG. 21, there is shown a perspective view of a caster assembly 30 that is adjustably affixed to the leg extending downwardly from the cross member 66 so as to contact the floor and provide support to the overall completed bed. Thus, in this embodiment, the upstanding stem 32 is threaded at 68 and is screwed into a corresponding internally threaded opening in the leg of the cross member 66. This embodiment is not, however, the preferred embodiment. The preferred embodiment is to affix the caster assembly to the furniture by means of a plastic bushing shown in FIG. 8 that is press fitted into the suitable opening in the piece of furniture. As stated, since the caster has considerable strength, it can be used in place of a conventional glide that is normally used with such cross members and yet the caster assembly 30 is also mobile and can readily be moved along a bare wood floor or a carpeted floor without suffering the breakage problems associated with the use of a normal glide.

Turning now to FIG. 22, there is shown a perspective view of a piece of furniture, namely a couch 152, that is supported by caster assemblies 154 of the present invention. As can be seen, the weight of the couch 152 is directed downwardly upon the caster assemblies 154 to be supported on the floor and, as has now been explained, the couch 152 can thereof be rolled in any direction without the need to align any offset rollers and thus the rollability of the couch 152 is greatly improved over the prior art casters used with such furniture. As also should be noted, the overall appearance of the couch 152 is pleasing with respect to the caster assemblies 154 since they blend in both functionally as well as esthetically with the appearance of the couch 152 since, as will be later described, the caster assemblies 154 are actually fitted into wooden or plastic legs that support the couch 152.

Next, in FIG. 23, there is a cross sectional view of a combined caster and leg assembly 156 constructed in accordance with the present invention. As can be seen, the caster and leg assembly 156 comprises a leg 158 and which is constructed out of wood or a plastic material. At the top surface or upper end 160 of the leg 158 there is a threaded stem 162 for securing the caster and leg assembly 156 to a piece of furniture, such as the couch 152 of FIG. 22, in order to affix the caster and leg assembly 156 thereto for supporting the piece of furniture on a floor. At the lower end 164 of the leg 158, there is formed a recessed area 166 that is cut or molded in the lower end 164.

Within the recessed area 166 there is located the caster 168 and which, as has been explained, includes a caster housing 170 that is fitted up into the recessed area 166 so as to not detract from the external appearance of the leg 158 as well as to provide a strong support for the piece of furniture. The caster housing 170 can be affixed within the recessed area 166 by means such as screws 172 whereby the caster 168 is contained substantially within the recessed area 166 with the spherical rollers 174 (three spherical rollers 174 are used) extending downwardly from the recessed area 166 in order to contact the flat planar surface of the floor 176. There is also a longitudinal, vertical centerline CL shown in FIG. 23 that centers the weight imposed by the furniture directly through the caster and leg assembly 156 since the centerline CL is centered with respect to the center points of the spherical rollers 174, thereby avoiding the offset and misaligned effect of the distribution of weight with normal casters used with furniture.

The small spherical balls 178 are also shown to be located within the annular, upwardly extending cup shaped recess 180 formed in the caster housing 170 so that the spherical balls 178 are free to move in and out of the chamber 182 intermediate the spherical rollers 174 and the upper surface 184 formed in the caster housing 170. That upper surface 184 has the same curvature or a slightly more shallow curvature than the exterior surface of the spherical rollers 174 in order to allow the free movement of the spherical balls 178 into and out of the chamber 182.

Accordingly, as can now be appreciated, the caster and leg assembly 156 provides a very strong support for the furniture since the weight of the furniture acts directly through the caster and leg assembly 156 without any offset between the direction of the weight and the contact with the floor and yet the caster 168 can be embedded into the wooden or plastic leg used for the furniture.

Turning now to FIG. 24, there is a cross sectional view of a further embodiment of the present invention where the wooden or plastic furniture leg 186 has its upper end 188 affixed to the frame of the furniture and is part of the furniture such that the recessed area 190 formed in the lower end 192 of the furniture leg 186 has been cut into the furniture leg 186. Thus, in this embodiment, the recessed area 190 can be pre-formed by the manufacturer of the furniture and the leg installed by that manufacturer or, alternatively, the present invention may be incorporated into the normal leg of a piece of furniture by cutting or shaping the recessed area 190 in order to retrofit the caster 168 of the present invention into an already constructed piece of furniture. Thus, a user already having the piece of furniture with a wooden or plastic leg can add the present caster 168 to upgrade that furniture and attain the advantages of strength and better appearance by adding the caster 168 of this invention to the leg 186 of the furniture.

Accordingly, the normal furniture leg 186 again holds the caster 168 to produce the caster and leg assembly 192 illustrated in FIG. 24. As with the prior embodiment, the longitudinal, vertical axis or centerline CL again is the direction and location of the acting weight of the furniture since it is equidistant from the center points of the spherical rollers 174 and therefore the weight of the furniture is not offset to cause harmful moment arms in the caster and leg assembly 194.

In FIG. 25 there is a cross sectional view of a still further embodiment of the present invention and where there is only one spherical roller 174 that is positioned in the caster 168 so as to have its center point along the longitudinal, vertical centerline CL of the furniture leg 196 so that, as with the prior embodiments, the weight of the piece of furniture acts downwardly along the centerline CL directly, without offset, to the floor 176. In this embodiment, the upper end 198 of the furniture leg 196 may also be directly affixed to the frame of the particular piece of furniture and the lower end 200 has formed therein a more narrow recessed area 202. Within that recessed area 202, there is provided a socket 204 that is affixed therein and which receives a stem 206 to affix the caster housing 208 to the furniture leg 196.

Again, the centerline CL of the caster and leg assembly 208 passes through the center point of the spherical roller 174 to insure that the weight of the furniture acts directly through the spherical roller 174 and not offset as with the conventional offset casters.

Therefore, with the use of the leg and caster assembly of the present invention, the support through the leg contacting the floor is strengthened and yet the overall appearance is enhanced by locating the caster contiguous to the smooth continual exterior surface of the lower portion of the furniture leg. In any of the embodiments of FIGS. 23-25, a glide can be attached to the caster housing in the manner shown and described with respect to FIGS. 4 and 7 hereof.

Turning now to FIG. 26, there is shown a perspective, cutaway view of a box spring 210 that has a caster 212 affixed thereto in accordance with the present invention. As can be seen, the box spring 210 is constructed of a angle iron lower edge 214 that extends around the perimeter of the box spring 210 forming an inwardly directed ledge that supports the wooden cross beams 216 of the box spring 210. The wooden cross beams 216 are also supported by metal T-shape cross supports 218 and a generally rigid wire structure 220 both stabilizes the inner stuffing 222 and supports the outer covering 224.

At each corner of the box spring 210 there is provided a plastic corner 226 that supports the upper wire 228 of the rigid wire structure 220 and which also rounds off the angle iron lower edges 214 to provide an overall rounded and pleasing appearance of the box spring 210. At the bottom of the plastic corner 226, there is a threaded hole (not shown). As alternative embodiments, the plastic corner 226 may be constructed of wood, metal or other suitable materials and instead of a threaded hole, there may be a pilot hole or no hole at all as will be later explained.

Turning to FIG. 27, taken along with FIG. 26, there is a side view of the caster 212 used with the FIG. 26 embodiment and where the caster 212 can be of the construction previously disclosed and discussed and which has a threaded stud 230 extending upwardly therefrom. Therefore, in order to affix the caster 212 to the bottom of the box spring 210, the threaded stud 230 is simply screwed into the threaded hole in the bottom of the plastic corner 226.

In the alternative embodiment, if the corner of the box spring 210 is wood, the threaded stud 230 can have wood screw threads and be screwed to the wooden corner by the aid of a small pilot hole or directly into the wood if there is no hole present at all. In any event, the caster 212 is screwed directly to the bottom of the box spring 210.

Turning finally to FIGS. 28 and 29, there is shown, respectively, a perspective view of a box spring 232 illustrating a further method of affixing a caster 234 to a box spring 232 and a perspective view of the caster 234 itself. As such, there is a female receptacle 236 formed in the bottom of the box spring 232 and, as shown, is in the configuration of a chevron, or L-shaped, that is, two straight portions 238 joined at an angle. The receptacle 236 can be provided as an insert embedded into the bottom of the box spring 232 or by other means, including, cutting the receptacle 236 therein. The internal, outer edges 240 can be tapered inwardly as the height of the receptacle 236 increases upwardly.

In FIG. 29, the male wedge member 242 is shown affixed to the caster 234 and which is generally L-shaped and dimensioned to interfit into the female receptacle 236. Thus, the external edges 244 of the male wedge member 242 are tapered outwardly toward the caster 236 in a complementary way to the inwardly tapered inner edges of the receptacle 236. Therefore, the caster 234 is affixed to the box spring 232 by simply pushing the male wedge member 242 up into the female receptacle 236 in the direction shown by the arrow W so that the male wedge member 242 is jammed into the female receptacle 236 to retain the caster 234 to the box spring 232 in a manner to be removable retained thereto. The affixation or junction between the caster 234 and the box spring 232 is further enhanced by the weight of the mattress and other covers that are placed atop of the box spring 232 since that weight further pushes the male wedge member 242 strongly into the female receptacle 236.

While the present invention has been set forth in terms of a specific embodiment or embodiments, it will be understood that the caster assembly herein disclosed may be modified or altered by those skilled in the art to other configurations. Accordingly, the invention is to be broadly construed and limited only by the scope and spirit of the claims appended hereto. 

1. A caster and leg assembly for supporting a piece of furniture positioned on a generally planar surface, said caster and leg assembly comprising a wooden or plastic leg extending downwardly and having a lower end with a recessed area formed therein, and a caster affixed within said recessed area, said caster having a housing containing at least one spherical roller, said at least one spherical roller adapted to contact the generally planar surface for supporting said caster and leg assembly, a plurality of spherical balls located intermediate said at least one spherical roller and said housing, said spherical balls adapted to move in a continuous circulatory path within said housing and to enter the area intermediate said at least one spherical roller and said housing by means of gravity, wherein said at least one spherical roller is freely rotatable under load to allow movement of the piece of furniture along the generally planar surface in any direction.
 2. A caster and leg assembly as defined in claim 1 wherein said caster has a central vertical longitudinal axis and said at least one spherical roller comprises one spherical roller having its center point located along said central vertical longitudinal axis.
 3. A caster and leg assembly as defined in claim 1 wherein said caster has a central vertical longitudinal axis and said at least one spherical roller comprises three spherical rollers having their center points spaced equidistant from said central vertical longitudinal axis.
 4. A caster and leg assembly as defined in claim 1 wherein said assembly is substantial housed within the recessed area of the leg to create an overall smooth, contiguous exterior profile of the leg and caster assembly.
 5. A caster and leg assembly as defined in claim 1 wherein the assembly includes a glide having a flat bottom that is attachable to and detachable from the housing to cover and uncover the at least one spherical roller.
 6. A caster and leg assembly as defined in claim 1 wherein the leg is affixed to the piece of furniture.
 7. A caster and leg assembly as defined in claim 1 wherein the leg has a lower surface having a hole formed therein and said housing has a stem extending upwardly therefrom that interfits into the hole in said leg.
 8. A caster and leg assembly as defined in claim 1 wherein the housing is affixed to the leg by means of screws.
 9. A method of affixing a caster onto a wooden or plastic furniture leg of a piece of furniture, said method comprising the steps of: forming a recessed area in the lower end of a wooden or plastic furniture leg, providing a caster comprising a housing containing at least one spherical roller, said at least one spherical roller adapted to contact a generally planar surface for supporting the piece of furniture, the caster having a plurality of spherical balls located intermediate said at least one spherical roller and said housing, said spherical balls adapted to move in a continuous circulatory path within said housing and to enter the area intermediate said at least one spherical roller and said housing by means of gravity, wherein said at least one spherical roller is freely rotatable under load to allow movement of the piece of furniture in any direction.; and affixing the housing of the caster within the recessed area of the furniture leg.
 10. The method of claim 9 wherein the step of forming a recessed area comprises molding a recessed area in the lower end of a plastic furniture leg.
 11. The method of claim 9 wherein the step of forming a recessed area comprises cutting a recessed area in the lower end of a wooden furniture leg.
 12. The method of claim 9 wherein the step of affixing the caster within the recessed area comprises affixing the caster so as to substantially enclose the caster housing within the recessed area.
 13. The method of claim 9 wherein the step of providing a caster comprising a housing containing at least one spherical roller comprises providing a caster comprising a housing containing three spherical rollers having center points forming a equilateral triangle.
 14. A leg member that elevates a piece of furniture above a generally planar surface, said leg member having an upper surface having a wedge member extending upwardly therefrom, said wedge member being configured to fit into a corresponding shaped receptacle formed in the piece of furniture.
 15. A leg member as defined in claim 14 wherein said wedge member has an upper end and comprises a pair of straight portions meeting at an angle and having external edges.
 16. A leg member as defined in claim 14 wherein the receptacle has internal edges that are inwardly tapered and said external edges of said wedge member taper inwardly toward said upper end.
 17. A leg member as defined in claim 14 wherein the wedge member is constructed of wood, plastic or metal.
 18. A leg member as defined in claim 14 wherein the leg member contains a unidirectional caster.
 19. A piece of furniture having a lower surface, a receptacle formed in said lower surface, said piece of furniture having a caster assembly affixed thereto, said caster assembly having a wedge member dimensioned to interfit into the receptacle, said male wedge member being forcefully jammed into the receptacle to retain the caster assembly to said piece of furniture.
 20. A piece of furniture as defined in claim 19 wherein the piece of furniture is a box spring.
 21. A piece of furniture as defined in claim 19 wherein the receptacle has internal edges that are inwardly tapered and said wedge member has external edges that taper inwardly generally corresponding to the inward taper of said receptacle.
 22. A piece of furniture as defined in claim 19 wherein said wedge member is a generally L-shaped configuration. 